Federal wildlife researchers report that up to 200 dead walruses were spotted from the air along the northwest coast of Alaska.

Researchers spotted 100 to 200 carcasses near Icy Cape, which juts into the Chukchi Sea about 140 miles southwest of Barrow.

For the second time in three years, thousands of walruses have congregated on Alaska's northwest coast as Arctic sea ice has receded beyond the shallow continental shelf, where the animals dive for clams and other benthic creatures.

The cause of death of the walruses is not known, but walrus experts say young animals can be crushed in stampedes when the animals are startled.

About 3,500 walruses were reported last week near Icy Cape.a